Device and working method for automatically changing work rolls, the back-up rolls and the intermediate rolls of a single-stand or multiple-stand strip mill

ABSTRACT

The invention relates to a device and a working method for automatically changing the sets of rolls comprising work rolls, backup rolls and intermediate rolls of a single-stand or multi-stand strip rolling mill, by means of a roll changing carriage ( 2 ) which can be displaced transversely with respect to the strip rolling stand ( 1 ) and a removal crossbar ( 3 ) provided for the removal of the set of backup rolls ( 10/11 ). In order to shorten the roll changing times and to automate the changing of the rolls, it is proposed that the removal crossbar ( 3 ) can be positioned on the roll changing carriage ( 2 ) and is provided with wheels ( 4 ) on which the removal crossbar ( 3 ) can be moved in working steps according to the invention out of the roll changing carriage ( 2 ) on guide rails ( 5 ) running parallel to the rolls ( 10/11 ) into the strip rolling stand ( 1 ) on the intermediate roll rails ( 8 ), and can be pulled out of the strip rolling stand ( 1 ) together with the set of backup rolls ( 10/11 ).

[0001] The invention relates to a device and a working method forautomatically changing the sets of rolls comprising work rolls, backuprolls and intermediate rolls of a single-stand or multi-stand striprolling mill, by means of at least one roll changing carriage which canbe displaced transversely with respect to the rolling stand into achanging position in line with the center of the strip stand and whichreceives the sets of rolls that can be pulled out on guide rails runningparallel to the rolls and displaces them transversely into a set-upposition, in which the replacement with a new set of rolls takes place,a removal crossbar that supports the upper backup roll being providedfor the removal of the set of backup rolls, which removal crossbar issupported on the lower backup roll when the work rolls and intermediaterolls have been removed and can be pulled out from the rolling standtogether with the set of backup rolls.

[0002] With the rolling stand, and as a result the entire rolling mill,at a standstill, there is of course a stoppage of production. This isparticularly unfavorable if, upstream or downstream of the rolling mill,there are other plants, for example a pickling plant, which couldactually continue running. The aim of each roll changing method istherefore to keep the downtimes of the rolling mill as low as possible.

[0003] In German Offenlegungsschrift DE 198 15 029 there is adescription of a roll changing method for a rolling stand of amulti-stand strip rolling mill, the rolling stands of which have workrolls and backup rolls. After completing the rolling of a first metalstrip, the rolling stand is stopped and the work rolls are removed. Ifthe rolling stand has intermediate rolls, the intermediate rolls arepreferably removed and installed together with the work rolls.

[0004] The backup rolls of this known strip rolling mill are changedwith the aid of a removal crossbar in the form of a slotted backup rollchanging frame, which is moved into the stand after removal of the setof work rolls. The work is largely carried out manually.

[0005] Another method and device for changing the work rolls and backuprolls of a strip rolling stand are described in DE 39 30 125 C2. Here,the changing of the rolls is performed to convert the rolling stand forexample from a six-roll system, that is a rolling stand with work rolls,intermediate rolls and backup rolls, into a four-roll system, with workrolls and backup rolls. For removal of the sets of rolls, roll changingcarriages which can be moved transversely with respect to the rollingstand and are equipped with guide rails and running rails for theremovable sets of rolls are used. At least FIG. 4 of the drawing of thisdocument shows the removal of the backup rolls with the aid of a removalcrossbar which rests on the lower backup roll and supports the upperbackup roll.

[0006] While the changing of the work rolls and also the intermediaterolls proceeds in a largely automated manner, in that, with the aid ofthe roll changing carriage and the corresponding pulling-out device, thesets of rolls are pulled out of the rolling stand onto the roll changingcarriage, where they are brought into a replacement position bytransverse displacement, the changing of the backup rolls largely takesplace manually. The removal crossbar is brought between the backup rollswith the aid of a crane, the upper backup roll is set down onto theremoval crossbar resting on the lower backup roll and the set of backuprolls is moved out on guide rails under the chocks of the lower backuproll. A large number of manual activities during the changing of thebackup rolls and crane work require a long downtime of the rolling mill.In addition, the crane work is more dangerous than the automaticchanging of the work rolls and/or intermediate rolls.

[0007] The aim of the present invention is to include also thepreviously manually performed changing of the backup rolls at leastpartly in the automated roll changing procedure and to use acorresponding device to provide a method for automatically changing thesets of rolls comprising work rolls, backup rolls and intermediate rollsof a single-stand or multi-stand strip rolling mill with which the rollchanging times can be reduced and the safety during roll changing can beincreased.

[0008] To achieve the object, an improved device of the type describedat the beginning is proposed, wherein the removal crossbar can bepositioned on the roll changing carriage provided for the changing ofthe work rolls and intermediate rolls and is provided with wheels onwhich the removal crossbar can be moved out of the roll changingcarriage into the strip rolling stand on guide rails running parallel tothe rolls and can be pulled out of the strip rolling stand together withthe set of backup rolls.

[0009] The interaction of the roll changing carriage with the removalcrossbar of the set of backup rolls and the special design of theremoval crossbar with its own wheels makes it possible for the changingof the backup rolls to be included in the automatic procedure. On theone hand, the provision of the removal crossbar on the roll changingcarriage shortens the roll changing time and makes crane workunnecessary, on the other hand the wheels on the removal crossbar makeit possible for the removal crossbar to be moved out of and into theroll changing carriage and out of and into the strip rolling stand.

[0010] According to a favorable feature of the invention, it is providedthat the wheels of the removal crossbar are mounted on both sides in theupper region of the latter and roll in the strip rolling stand on theraisable and lowerable intermediate roll rails of the upper intermediateroll. This allows the removal crossbar to be displaced from the changingcarriage on guide rails of the same height directly onto the raisableand lowerable intermediate roll rails positioned in the upper position,from where they can be set down on the lower backup roll or the chock ofthe latter by lowering the intermediate roll rails. Together with theplaced-on upper backup roll, the set of backup rolls can then be movedout from the strip rolling stand manually or in an automated manner, thewheels of the removal crossbar being free and the moving out takingplace on the guide rails underneath the chocks of the lower backup roll.

[0011] The removal crossbar is advantageously provided with a roll pin,which can be coupled to the pulling-out device of the roll changingcarriage.

[0012] If, according to a further feature of the invention, it isprovided that the removal crossbar can be positioned laterally next tothe set of work rolls and intermediate rolls on the roll changingcarriage and, by transverse displacement of the roll changing carriage,can be brought into a position in relation to the strip rolling stand inwhich the guide rails of the roll changing carriage are in line with theraised intermediate roll rails in the strip rolling stand, this proposalalso serves for shortening the roll changing times. The removal crossbarno longer needs to be laboriously inserted into the strip rolling standwith the aid of a crane; it is ready-suspended in the roll changingcarriage and only needs to be displaced by transverse displacement ofthe roll changing carriage into the position in which the guide rails onwhich the wheels of the removal crossbar roll are in line with theintermediate roll rails.

[0013] With the device according to the invention, the working method ofthe invention which comprises the sequence of the following workingsteps can be carried out:

[0014] The rolling stand is hydraulically opened up by opening the rollgap. The roll changing carriage is moved to the center of the stand onrails running laterally next to the strip rolling stand, parallel to thedirection of rolling, so that the work rolls and intermediate rolls canbe coupled to the pulling-out device and pulled into the roll changingcarriage. Together with the work rolls and intermediate rolls, the rollchanging carriage is then transversely displaced, the removal crossbarthat is provided laterally of the work rolls and intermediate rolls onthe roll changing carriage being simultaneously brought into the centerof the stand by transverse displacement of the roll changing carriage,so that the guide rails and intermediate roll rails are in line.

[0015] The removal crossbar is moved out of the roll changing carriageon its wheels and, guided on the intermediate roll rails, is moved intothe strip rolling stand. As soon as the removal crossbar has reached itsposition in the strip rolling stand, the intermediate roll rails arelowered, whereby the removal crossbar is set down on the lower backuproll or the chock of the latter. Then, by lowering the intermediate rollrails, the upper backup roll can be set down on the removal crossbar.During these working steps, the roll changing carriage with the workrolls and intermediate rolls is transversely displaced, whereby the workrolls and intermediate rolls reach a replacement position, from whichthey can be replaced with new sets of rolls by the crane. The set ofbackup rolls supported in the meantime on the removal crossbar is movedout from the strip rolling stand on guide rails and replaced by cranewith a new set of backup rolls, which is moved into the strip rollingstand.

[0016] At the same time as the changing of the backup rolls, new workrolls and intermediate rolls were placed in the roll changing carriage.

[0017] The upper backup roll of the set of rolls and the intermediateroll rails are raised again, the intermediate roll rails engaging underthe wheels of the removal crossbar and lifting the latter off the lowerbackup roll. The roll changing carriage then moves into position andpulls the removal crossbar on the intermediate roll rails out onto theguide rails of the roll changing carriage. By subsequent transversedisplacement of the roll changing carriage, the new set of work rollsand intermediate rolls is brought into the center of the stand andpushed into the stand. After closing the roll gap, the changing of thework rolls, intermediate rolls and backup rolls is complete.

[0018] With the invention, the downtimes of the rolling mill areshortened considerably. The greater availability of the rolling millthat is consequently achieved increases the output and consequentlyimproves the cost-effectiveness. The automatic feeding of the removalcrossbar is additionally much safer for the operating personnel incomparison with the conventional working practice.

[0019] An exemplary embodiment of the invention is described below onthe basis of the drawing, in which:

[0020]FIG. 1 shows a side view of a six-roll strip rolling stand duringthe changing of the backup rolls with the aid of the roll changingcarriage and the removal crossbar,

[0021]FIG. 2 shows the removal crossbar,

[0022]FIG. 3 shows a section through the strip rolling stand during thechanging of the backup rolls with the upper backup roll placed on theremoval crossbar and

[0023]FIG. 4 shows a section through the strip rolling stand during thechanging of the backup rolls with the removal crossbar raised.

[0024] Represented in a side view in FIG. 1 is a section taken centrallythrough a known six-roll strip rolling stand 1, in the case of which theset of rolls comprising work rolls and intermediate rolls has alreadybeen removed. The set of rolls was pulled out from the strip rollingstand 1 in a known way with the aid of the roll changing carriage 2 anddisplaced transversely, i.e. perpendicularly in relation to the plane ofthe drawing, on the roll changing carriage 2.

[0025] For the changing of the backup rolls, according to the inventionthe removal crossbar denoted by 3 is used. As FIG. 1 shows, this removalcrossbar 3 is positioned on the roll changing carriage 2 laterally nextto the set of rolls comprising work rolls and intermediate rolls, andwas moved into a position centrally in relation to the strip rollingstand 1 by transverse displacement of the roll changing carriage 2. Theset of rolls comprising work rolls and intermediate rolls cannot be seenin FIG. 1; it is concealed by the removal crossbar 3 in the foreground.

[0026] The roll changing carriage 2 with the removal crossbar 3 is readyfor use in front of the strip rolling stand 1; the prepared removalcrossbar 3 is suspended with wheels 4 on guide rails 5 of the rollchanging carriage 2. As shown in the representation of a detail in FIG.2 of the drawing, the removal crossbar 3 is designed in a C-shapedmanner, so that the moving in and out of the removal crossbar 3 is alsomade possible when the strip is in the strip rolling stand 1. Arrangedin each of the four upper corner regions of the removal crossbar are thewheels 4, with which the removal crossbar 3 is suspended in the guiderails 5 (FIG. 1) of the roll changing carriage 2. Attached on the sideof the removal crossbar 3 that is on the right—in the plane of thedrawing—is a roll pin 6, which, corresponding to the gripping device 7of the roll changing carriage 2, makes it possible for the removalcrossbar 3 to be automatically integrated in the changing of the backuprolls.

[0027] In the left half of the drawing in FIG. 1, the removal crossbar 3is represented in the strip rolling stand 1, where it fills the space ofthe removed set of rolls, comprising intermediate rolls and work rolls.Starting from the roll changing carriage 2, to bring the removalcrossbar 3 from the preparation position represented in the right halfof the drawing into the position in the strip rolling stand 1,represented in the left half of the drawing, the intermediate roll rails8 of the same height in the strip rolling stand 1 and the guide rails 5in the roll changing carriage 2 are brought into a position in whichthey are in line with one another. In this position, the removalcrossbar 3 can be moved automatically from the roll changing device 2via the guide rails 5 and the intermediate roll rails 8 into the striprolling stand 1. By subsequent lowering of the intermediate roll rails8, the removal crossbar 3 is lowered onto the chocks 9 of the lowerbackup roll 10 and set down there. This operation is represented in FIG.3 of the drawing. Pins 11 on the underside of the removal crossbar 3engage in bores 12 on the chock 9 and stabilize the removal crossbar 3.The no longer required roll changing carriage 2 is moved by transversedisplacement to the side to such an extent that the window of the striprolling stand 1 is free for changing the backup rolls.

[0028] Once the removal crossbar 3 has been set down, the upper backuproll 13 is hydraulically set down on top of the removal crossbar 3 andlikewise secured by pins 15 engaging in bores 14 of the chocks 16. Theentire set of backup rolls can then be moved out of the strip rollingstand 1 in a known way on the lower moving-out rails 17 (FIG. 1) and bechanged manually with the aid of a crane (not represented).

[0029] At the same time as the method sequence described above, theremoved intermediate rolls and work rolls were replaced; a new setcomprising intermediate rolls and work rolls was prepared on the rollchanging carriage 2. A new set of backup rolls 10/13 is then moved intothe strip rolling stand 1 in the reverse procedure to that describedabove for the removal of the old set of backup rolls. The backup rolls10/13 are brought into position; the upper backup roll 13 ishydraulically raised, so that the chocks 16 are lifted off the removalcrossbar 3. The removal crossbar 3 is lifted off the lower chocks 9 bymeans of the raised intermediate roll rails 8 and is then suspendedfreely from the intermediate roll rails 8 in the strip rolling stand 1,as represented in FIG. 4 of the drawing.

[0030] The roll changing carriage 2, which has in the meantime beentransversely displaced into position, grips with its roll changingdevice 7 the roll pin 6 on the removal crossbar 3 and pulls the latteron the intermediate roll rails 8 and, via the aligned guide rails 5, outof the strip rolling stand 1 into the roll changing carriage 2.

[0031] By renewed transverse displacement of the roll changing carriage2, the new set of rolls comprising intermediate rolls and work rolls,which is in the preparation position laterally next to the removalcrossbar 3, is brought into a position centrally in relation to thestrip rolling stand 1, from which the set of rolls can be moved into thestrip rolling stand 1. This operation is conventional and therefore doesnot need to be described any further here. After closing the roll gap,the strip rolling stand 1 is ready for use.

1-5. (cancelled)
 6. Apparatus for changing sets of rolls in a stand of astrip rolling mill having at least one roll stand having a pair of workrolls for rolling a strip moving in a rolling direction, a pair ofintermediate rolls, and a pair of backup rolls consisting of a lowerbackup roll and an upper backup roll, the apparatus comprising: a rollchanging carriage which can be displaced parallel to the rollingdirection into a changing position aligned with a respective said rollstand, the carriage having guide rails extending parallel to the rollsand being movable parallel to the rolling direction into a set-upposition in which the rolls can be replaced; and a removal crossbarhaving wheels for supporting the crossbar on the guide rails and movingthe crossbar out of the carriage and into the roll stand between thebackup rolls after the work rolls and the intermediate rolls have beenremoved, the crossbar being supportable on the lower backup roll andhaving means for supporting the upper backup roll so that the crossbartogether with the backup rolls can be pulled out of the roll stand. 7.Apparatus as in claim 6 further comprising a pair of intermediate rollrails in the roll stand, the guide rails in the carriage aligning withthe intermediate roll rails when the carriage is in the changingposition, the wheels being mounted on both sides of an upper region ofthe crossbar, whereby the removal crossbar can be moved from thecarriage into the roll stand, the intermediate roll rails being raisableand lowerable so that the crossbar can be supported on the lower backuproll.
 8. Apparatus as in claim 6 further comprising a pulling-out devicemounted on the roll changing carriage, the crossbar having a roll pinwhich can be coupled to the pulling-out device.
 9. Apparatus as in claim1 wherein the carriage can accommodate the work rolls and theintermediate rolls next to the crossbar in the direction of movement.10. A method for changing sets of rolls in a stand of a strip rollingmill having at least one roll stand having a pair of work rolls forrolling a strip moving in a rolling direction, a pair of intermediaterolls, and a pair of backup rolls consisting of a lower backup roll andan upper backup roll, the method comprising: opening up the rolls toform a roll gap; displacing a roll changing carriage into a positionaligned with a roll stand and coupling the carriage to the work rollsand the intermediate rolls; pulling the work rolls and the intermediaterolls out of the roll stand and onto the roll changing carriage;displacing the carriage parallel to the rolling direction until acrossbar provided on the carriage laterally of the work rolls andintermediate rolls is aligned with the roll stand; moving the removalcrossbar into the roll stand on intermediate rails roll provided in theroll stand; lowering the intermediate roll rails so that the removalcrossbar is supported on the lower backup roll; lowering the upperbackup roll so that the upper backup roll is supported on the removalcrossbar; displacing the carriage to a set-up position where the workrolls and the intermediate rolls can be replaced; moving the backuprolls and the crossbar out of the roll stand on rails; replacing thebackup rolls with new backup rolls using a crane; moving the new backuprolls and the crossbar into the roll stand; replacing the work rolls andthe intermediate rolls on the carriage with new work rolls andintermediate rolls; raising the intermediate roll rails with the removalcrossbar; moving the roll changing carriage parallel to the rollingdirection until a pair of guide rolls on the carriage are aligned withthe intermediate roll rails; moving the removal crossbar out of the rollstand onto the guide rails; displacing the carriage parallel to therolling direction until the new work rolls and intermediate rolls arealigned with the roll stand; pushing the new work rolls and intermediaterolls into the stand; and closing the roll gap.